Energy-efficient Dual-Fuel Burners
Mannesmann Precision Tubes works with many different measures to minimize process-related emissions in production. Among the most important emitters in our plants are the furnaces, in which the structure and mechanical-technological properties of steel tubes are specifically adjusted. At our nine production sites we operate 22 furnaces which are heated by a total of over 1,000 recuperative burners. Optimizing burner technology thus offers great potential for saving emissions and resources.
With iRecu®, Kueppers Solutions has developed a pioneering technology whose market launch was supported by Mannesmann Precision Tubes as one of the first users in the ongoing production process. Genuine pioneering work - and an important component for even more sustainable production at our plants.
iRecu®- The innovative recuperative burner from our partner Kueppers Solutions
The new burner technology differs from conventional models in two significant ways:
3D printing enables increased energy efficiency
The iRecu® has particularly complex geometries in its internal structure that cannot be reproduced by the most recent conventional manufacturing processes. Manufacturing the burner components using 3D printing enables particularly efficient heat transfer through optimized gas/air flow. This alone can reduce the natural gas consumption of the furnaces by up to 15 % while heat generation remains the same, and corresponding emission savings can be realized in furnace operation.
Dual-Fuel structure makes burner "H2 ready"
Even greater emission savings can be realized in the future through possible dual-fuel operation. Separate connections and an integrated mixing unit make it possible to use hydrogen instead of natural gas or to use a mixture of both gases as fuel for furnace heating - flexibly and without the need of another plant conversion. When hydrogen becomes available in sufficient quantities, this will pave the way for an even more significant step toward sustainable manufacturing.
The pilot project - Comprehensive testing in the laboratory and ongoing plant operation
The starting point of the pilot project was a proof-of-concept which, after the furnace-specific prototype development by Kueppers Solutions, included a series of tests lasting several days at the Gas und Wärmeinstitut Essen e.V. (GWI). In the process, the prototype and one of our existing burners from Hamm were subjected to several representative test series.
Aim of these tests was to determine the operating point of the new burner system at which the same process temperatures are achieved that existing burners with an output of 35 kW produce. At 30 kW, the operating point of the prototype was significantly lower than the existing burner.
The operation of the prototype with up to 100 Vol.-% hydrogen as fuel gas and the resulting influence on the heat treatment process were also investigated. The measurements confirmed that the temperature and heat distribution along the steel tube do not change as a result of the use of hydrogen, so that no change is to be expected in the real process.
The promising results were the basis for testing the iRecu® in the ongoing furnace operation at the precision tube plant in Hamm. At our continuous furnace, a first existing burner was replacd by an iRecu® burner in the most energy-intensive, first furnace zone. This was then operated and cycled in parallel with the other existing burners over a period of 43 days. Both the exhaust temperature at the exhaust gas stub and the exhaust temperature of the heat exchanger were measured using thermocouples and recorded with a mobile long-term measuring device. For direct comparison, the exhaust gas temperatures of the two neighboring existing burners were also measured and recorded.
On the basis of the measured temperature curves, it was possible to determine a fuel gas saving of 12.3 % by using the iRecu® burner over the period under consideration during plant operation. The field test at the plant thus confirms the fuel gas savings derived under laboratory conditions at GWI. Conversion of the furnace to iRecu® burners can therefore be expected to result in gas savings between 12.3 % and 14.3 %.
Achieved and potential savings
After converting the 233 burners at our Hamm site alone, the measured natural gas savings per burner will result in an annual saving of 900 tonnes of CO2. A potential that we will consistently realise.
In Hamm, we have now converted the first furnace zones of three heat treatment furnaces to iRecu® burners. But the project is also being scaled up across all sites: Further burners are being installed at the German plant in Holzhausen as well as in our French plant in Saint-Florentin.
For our entire Mannesmann Precision Tubes Group, converting all burners alone results in a potential emission reduction of 4,900 t/a CO2 already in natural gas operation. Complete conversion to green hydrogen would mean an additional 28,100 t/a of CO2 savings - and would be another enormous step toward low emission production.
